The invention relates to an electrical pin for solderless insertion into metallized apertures of a circuit board, comprising a shaft having a longitudinal axis and a tapered end, an elastically deformable press-fit portion provided at the shaft and spaced from the tapered end thereof, the press-fit portion comprising at least three contact areas extending substantially parallel with the axis of the shaft and over the whole length of the press-fit portion, said contact areas equally spaced from said axis and defining a first diameter larger than a diameter of each one of said apertures in the circuit board, and a transition portion provided at the shaft and connected to the press-fit portion in an inserting direction, the transition portion also comprising contact areas connected to those of the press-fit portion, tapering in inserting direction and spaced from the tapered end of the shaft.
An electrical pin of this kind is known from DE-3909310-A1. Valleys are formed in the press-fit portion and in the transition portion whereby a pair of webs are formed connected by a bridge. At the outer edges of both webs contact areas are formed, which during the inserting step of the pin into an aperture of the circuit board are elastically pressed against the inner surface of the aperture.
A similar art is known from DE-3804041-A1, which teaches that by the transition portion a soft insertion of the pin into the aperture of the circuit board is achieved. A leading portion having a square or cylindrical cross-section which is remarkably less than the aperture of the circuit board is arranged between the transition portion and the tapered end of the pin.
European Patents 0059462, 0221092 and U.S. Pat. No. 3,837,063 show pins of a similar construction.
To install a circuit board with such electrical pins automatically, the pins must be relieved from a carrier strip, then aligned with the aperture and pressed into the latter. However, in high speed insertion machines problems arise due to the precise alignment of each pin with respect to the predetermined aperture. During a first positioning step the pin must be restrictively guided. Then, when entering the aperture the pin must be released in order to enable self-alignment. Thereafter the pin is engaged again by a pressing tool to press it into the aperture. Because the pins are handled one by one, the operating speed of the machine is limited.